电子政务系统中的访问控制研究

该文根据对一些应用中的访问模式及特点的分析,提出了将PAC与CAP相结合的新型访问控制模型,该模型能够很好地对系统中的数据对象进行保护。     

Hybrid polling and contention access scheduling in IEEE 802.11e WLANs

Supporting real time applications over local area wireless access networks requires features and mechanisms that are not present in the original IEEE 802.11 standard for WLANs. Therefore, several quality of service (QoS) enabling mechanisms have been added to the MAC layer in the new IEEE 802.11e standard. However, the standard does not mandate a specific QoS solution and intentionally leaves it to developers and equipment vendors to devise such schemes. We present a solution that employs the controlled access mechanisms of the 802.11e to provide per-session guaranteed QoS to multimedia sessions. We introduce a framework that centralizes the task of scheduling uplink and downlink flows in the access point through the new concept of virtual packets. We propose a fair generalized processor sharing based scheduler, integrated with a traffic shaper, for scheduling controlled (polling) and contention access durations. Through analysis and experiments we demonstrate that our solution provides guaranteed fair access for multimedia sessions over WLANs.     

Polymers with pH-dependent solubility: possibility of use in the formulation of gastroresistant and controlled-release matrix tablets

Polymers usually utilized for gastroresistant film coating of tablets or pellets such as cellulose acetate phthalate (CAP), cellulose acetate trimellitate (CAT), hydroxypropylmethylcellulose phthalate (HPMCP), and Eudragit L and S were used in the preparation of drug/polymer matrix tablets. These tablets were prepared either by direct compression of both powders or by the formulation of microspheres that were then compressed. The microspheres were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffractometry analyses. Dissolution studies were finally carried out to verify if the tablets possessed gastroresistant or controlled-release characteristics. Except for Eudragit L, the polymers can be used under certain conditions in the formulation of modified-release tablets.     

PECAP: Priority-Based Delay Alleviation Algorithm for IEEE 802.15.4 Beacon-Enabled Networks

A new priority-based algorithm for IEEE 802.15.4 beacon-enabled networks is proposed in order to alleviate an end-to-end delay while maintaining energy efficiency. In this paper, the active period is temporally increased to reduce the sleep delay that makes up a large portion of the end-to-end delay. Nodes having high-priority packets request the coordinator to execute an extended contention access period by sending a priority toning signal. The simulation results show that the proposed algorithm alleviates the end-to-end delay of high priority packets.     

代建制项目的信息集成管理研究

信息管理往往是工程项目管理中的薄弱环节,本文针对代建制项目的特点,提出了代建制项目中信息集成应以项目管理公司为核心,以现代化的网络技术为手段,通过集成化项目管理信息系统(IPMIS)实现。在论述了信息集成的必要性之后,从时间、目标、功能和主体四个维度进行分析,并建立了较为系统的集成化项目管理信息系统框架模型。     

一种基于LINUX操作系统的安全增强实现思路

针对传统操作系统存在的安全缺陷,作者提出了一个将几种安全策略和机制有机结合,很好地弥补安全缺陷的基于LINUX的安全增强实现思路。     

约界参数CAP对大型钢结构系统可靠性分析的影响

为提高大型钢结构系统可靠性分析方法的效率和精度,提出约界参数CAP(Control ambit parameter)的概念,通过对立体车库大型钢结构系统的有限元参数化建模、主要失效模式的算法研究,建立了该失效模式的安全余量方程。在此基础上,编制分析计算软件并对立体车库钢结构可靠性进行定量计算,结合算例分析其在大型钢结构系统可靠性中对失效准则、失效模式和系统失效概率的影响,得出应根据结构规模和特征选取适合的CAP值才能保证真正反映系统实际失效概率。     

ADS-4空气-硼酸夹带试验研究

为研究真实工况下的ADS-4夹带现象,以CAP1400为原型按1∶1的比例设计搭建了FATE试验台架。硼酸溶液用来模拟反应堆堆芯中真实工况的流体。利用数据采集系统和高速摄像仪记录夹带过程,将所得的试验数据与纯水工况和已有的模型进行比较。结果表明：对于夹带起始和稳态夹带率,硼酸工况和纯水工况的试验结果与之前的模型均不同。硼酸工况和纯水工况的现象基本相似,弗劳德数随夹带起始液位的增加而减小。两者的夹带起始均有回滞效应,且自上而下的夹带起始更易发生。硼酸工况和纯水工况之间也存在着差异,这主要是由于两者的物理特性参数不同而造成的,尤其是密度和黏度的影响。     

卷烟滤嘴棒填充纸及嘴棒性能的研究

以卷烟厂废滤嘴棒为原料,对其进行打浆处理,并与植物纤维配抄卷烟滤嘴棒填充纸(CAP纸).实验结果表明,废滤嘴棒经过处理后可以作为CAP纸的原料,并且抄造的CAP纸可使滤嘴棒既具有纸质填充材料吸附性好的优点,又具有醋酸纤维良好弹性和吸味的特点.应用试验结果表明,在吸阻相同的情况下,CAP纸可使滤嘴棒具有较好的降低卷烟焦油性能.     

Java卡调试平台的研究及实现

从计算机语言源代码级调试的一般性原理和概念入手,深入分析了Java卡规范和Java平台调试体系规范,提供了一个合理的Java仁调试平台设计方案。此外,文章还详细描述了调试平台实施所涉及到的要点,包括运行时调试信息的组织方式和使用方法、断点实现技术、单步调试实现技术等。实验结果表明,该调试平台设计方案是可行的。